Underground Services and CAT and Genny Toolbox Talk
Hitting a buried power cable or gas main can kill you instantly or start a fire. Even a fibre or water line strike can cost thousands and shut down a street. Every dig starts with finding out what is in the ground.
Takes about 6 minutes, plus a 5-question quiz.
Key points to read out
- Get utility plans from every service owner before digging, and follow HSE guidance HSG47.
- Plans are a guide only. Services move, depths change, and private lines are often not on any plan.
- Scan the area with a CAT and Genny before breaking ground, and mark the services clearly.
- Share the plans and the marks with everyone on the dig, including the machine operator and any subcontractors, before work starts.
- Keep the marks visible. If rain, traffic or digging wipes them out, stop and get them re-marked.
- Hand dig trial holes, and keep mechanical excavators at least 0.5 m away from located services.
- Look for clues: meter boxes, pits, lids, street lights and patched pavement all point to buried services.
- Keep the plans and locate records on site and in date.
- If you strike a service: stop, keep everyone back, and call the asset owner straight away.
- For a gas strike: move everyone away, no smoking or ignition sources, and call emergency services.
- If a machine hits a power cable, the operator stays in the cab and everyone else keeps well back until the network says it is safe.
- Never fill in or cover a damaged service, even a small nick in the coating. Report it so it can be repaired properly.
Questions to ask the crew
- Do we have current service plans for this dig?
- Which services are close to where we are digging today?
- How close can the machine get before we switch to hand digging?
- What would you do if we hit a gas line?
- Who has the locate records, and does everyone on the dig know where they are?
Reference: HSE guidance HSG47, Avoiding danger from underground services
How to run this talk
- Run the talk at the dig site with the service plans and locate marks in front of the crew.
- Walk the marks together and point out clues such as pits, meters, lids and patched pavement.
- Make sure the machine operator and any subcontractors have seen the plans.
- Agree exactly where the machine stops and hand or vacuum digging starts.
- Practise the strike response: who calls the asset owner and emergency services, and where everyone goes.
- Record attendance and the plan reference numbers on the sign-in sheet.
Underground Services and CAT and Genny quiz
Ask these after the talk. Answers are underneath each question.
What is the first step before any digging, even with a shovel?
- Get utility plans from every service owner and plan the dig to HSG47
- Start digging slowly and watch for cables
- Ask the person who last worked here
Answer: A. You cannot see what is buried, so the dig starts with finding out what services are there and who owns them.
You have the plans. How accurate are they?
- Exact to the centimetre
- A guide only, because services move and private lines are often missing
- Accurate for depth but not position
Answer: B. Plans show approximate positions, so services must be located on site and exposed before machines dig near them.
The excavator is getting close to a located service. What should happen?
- Keep digging with the bucket but go slower
- Switch to hand digging, keeping the excavator at least 0.5 m from the service
- Dig faster so the service is uncovered quickly
Answer: B. Machines can hit and rupture services before the operator feels anything, so you expose them by hand or vacuum.
You smell gas after striking a pipe. What do you do?
- Try to plug the pipe with tape
- Move everyone away, remove ignition sources, and call 999 and the gas emergency line
- Fill the hole back in to stop the smell
Answer: B. Never try to fix a gas leak yourself: gas can overcome you in the trench or ignite, so get clear and let the network make it safe.
An excavator hits a buried power cable. What should the operator do?
- Jump out and run
- Stay in the cab and keep everyone back until the network says it is safe
- Climb down and check the damage
Answer: B. The ground and machine can be live, so staying in the cab avoids stepping into a path for the current.
Questions about underground services and cat and genny
How do I find out what is underground before digging?
Get plans from every utility that may have services in the area, scan the site with a cable avoidance tool (CAT) and signal generator (Genny), and hand dig trial holes to confirm positions. HSE guidance HSG47, Avoiding danger from underground services, sets out this approach.
Are utility plans accurate enough to dig by?
No. Plans are a guide only: services move during other works, depths change when ground levels change, and private lines are often not shown. Always locate services on site and expose them by hand or vacuum before machines dig nearby.
How close can you dig to an underground service with a machine?
HSE guidance HSG47 says mechanical excavators should not be used within 0.5 m of a located service; dig by hand inside that distance to expose it. Asset owners may set larger distances for high pressure gas or high voltage cables.
What should you do if you hit an underground service?
Stop work, keep everyone back and contact the asset owner straight away. For gas, move everyone away, remove ignition sources and call 999 and the gas emergency line; for power, the operator stays in the machine. Never cover up a damaged service, even a small nick.
Sign-in sheet
Print this page or download the sign-in sheet. Or run it in the app and the crew signs on the phone.
| Name | Company | Signature |
|---|---|---|
Get it signed
Run this talk in the app. The crew signs on your phone and you get a dated attendance record as a PDF.